ECOLOGICAL PYRAMIDS ECOLOGICAL PYRAMIDS • If we arrange the organisms in a food chain according to their trophic levels‚ we often form a pyramid with a broad base representing primary produces & only a few individuals in the higher trophic level. • This pyramid arrangement is especially true if we look at the E content of an ecosystem. • Following the 2nd law of thermodynamics‚ less food E is available to the top trophic level than is available to the preceding level. • For example‚ it takes
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and easily available. vi)Have moderate rate of combustion 5 CALORIFIC VALUE: The amount of heat energy released on complete combustion of 1 kg of a fuel in air or oxygen is called its calorific value. It is expressed in kJ/kg. Hydrogen has the highest calorificvalue :150000 KJ/Kg. * Table of calorific value of different fuels is given on pg 73 of the NCERT book. 6 CONDITIONS NECESSARY FOR COMBUSTION: a)Presence of oxygen or air b)Presence of combustible substance c)Correct ignition temperature
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boiler surface and the surroundings. By Newton’s law of cooling it is assumed constant. The 1st law balance for the boiler at time t (secs) is + Rate of change of internal energy of the boiler and contents. Therefore‚ Where MC (kJ/ K) is the heat capacity of the boiler which in this simplified development is assumed constant. So‚ when being heated‚ (1) and when cooling‚ (2) At a value of T1 on the lot of the measured heating curve and at a value T2
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3 Work‚ Power and Energy At the end of this section you should be able to: a. b. c. d. e. f. describe potential energy as energy due to position and derive potential energy as mgh describe kinetic energy as energy due to motion and derive kinetic energy as mv2/2 state conservation of energy laws and solve problems where energy is conserved define power as rate of energy transfer define couple‚ torque and calculate work done by variable force or torque solve problems where energy is lost due to friction
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Introduction For this experiment‚ we are going to determine the effect of temperature on solubility‚ to be done in a chemical by dissolving a solute in a definite amount of solution which is saturated. Specifically‚ the goal of this experiment is to prepare a saturated solution of Na2C2O4 in water at different temperatures‚ determine the effect of temperature in solubility‚ and to apply Le Chatelier’s Principle. We can do all this by simply titrating a certain amount of standard KMnO4‚ and measuring
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from 80.16 - 88.20%; carbohydrate values from 53.29 - 59.01%; and calorific values ranged from 1344.00 – 1399.00 kJ/g (316.66-329.76 cal/g) for the sweet potato leaves. For M. oleifera leaves‚ crude protein was 27.51%‚ crude fibre was 19.25%‚ crude fat was 2.23%‚ ash content was 7.13%‚ moisture content was 76.53%‚ carbohydrate content was 43.88%‚ and the calorific value was 1296.00 kJ/g (305.62 cal/g). Elemental analysis of the leaves in mg/100g dry matter (DM) indicates the sweet potato leaves
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6. a) ∆G’°=-RTlnKeq’=-8.315Jmol∙K×298K×ln1.97=-1.68 kJ/mol b) ∆G’=∆G’°+RTlnglucose-6-phosphate fructose-6-phosphate=-1.68kJmol+8.315Jmol∙K×298K×ln0.51.5 =-4.40kJ/mol c) ∆G’° is the standard energy change at the given temperature and fixed concentration of chemicals in the reaction. (For this reaction‚ both glucose-6-phosphate and fructose-6-phosphate are at 1M) . In contrast‚ ∆G’ is a variable energy change for different sets of reactant and product concentrations‚ which can be calculated
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Determining the Enthalpy of a Chemical Reaction All chemical reactions involve an exchange of heat energy; therefore‚ it is tempting to plan to follow a reaction by measuring the enthalpy change (∆H). However‚ it is often not possible to directly measure the heat energy change of the reactants and products (the system). We can measure the heat change that occurs in the surroundings by monitoring temperature changes. If we conduct a reaction between two substances in aqueous solution‚ then the
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References: [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] Weber KJ‚ Blakers AW. Semiconductor Processing. International patent application PCT/AU01/01546‚ 2001. Weber KJ‚ Blakers AW‚ Stocks MJ‚ Babaei JH‚ Everett VA‚ Neuendorf AJ‚ Verlinden PJ. A novel low cost‚ high efficiency micromachined silicon solar cell. Electron Device Lett. 2004; 25:37. Blakers AW‚ Stocks MJ‚ Weber KJ‚ Everett V‚ Babaei J‚ Verlinden P‚ Kerr M‚ Stuckings M‚ Mackey P. Sliver® solar cells. Proc.
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UNIVERSITY OF PRETORIA UNIVERSITEIT VAN PRETORIA ` DEPARTEMENT OF CHEMISTRY DEPARTMENT CHEMIE DATE / DATUM: TIME / TYD: MARKS / PUNTE: 2008.05.30 120 min 80 Outeursreg voorbehou Fakulteit Natuur- en Landbouwetenskappe CHM 171 EXAMINATION / EKSAMEN Internal Examiners / Interne Eksaminatore: External Examiner / Eksterne Eksaminator: Surname and Initials Van en Voorletters Signature Handtekening Dr FR Vogel Dr RJ Bowen Dr EMM Venter Prof WJ Schoeman Student number Studentenommer Marks
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